Advanced Electric Machines – University R&D Role

Asst. Prof. Eric L. Severson

University of Wisconsin-Madison

eric.severson@wisc.edu

Wisconsin Electric Machines and Power Electronics Consortium• Founded in 1981 with 4 corporate sponsors

• Founders: Prof. Don Novotny and Prof. Tom Lipo

• People• 5 Faculty (and growing!)• 3 Emeritus Faculty• 40 PhD Students(on campus)• 13 MS Students(on campus)• 97 off campus students• 7 Visiting scholars• > 510 alumni

• Degrees granted• > 425 MS• >160 PhD

Electric Machines

ControlPower

Electronics

WEMPEC

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High Performance

Motors

Power Electronics

Magnetic Levitation

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My Research Interests: design and control of

1kW - 1MW+100 - 300,000 RPM

Flywheel Energy Storage

Industrial Compressors

Electric Turbochargers

Spindle Tools

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Power-Speed Capability of Electric Machines

© University of Wisconsin Board of Regents

Highest Speed-Power Motors (with bearings)1

[1] D. Gerada et al, “High-speed electrical machines: Technologies, trends, and developments,” IEEE Trans on Ind. Elec., 2013

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Magnetically Levitated Motor Systems

© University of Wisconsin Board of Regents

Our Research Focus Areas

• Reduce torque/power • by 25% – 50%

• Decrease efficiency

• Expensive to manufacture

© University of Wisconsin Board of Regents 6

Legacy Bearingless Motors Use Two Windings

[1] G. Munteanu, A. Binder, and T. Schneider., “Loss Measurement of a 40 kW High-Speed Bearingless PM Synchronous Motor,” ECCE 2011.

Image from [1]

• Same coils for force and torque

• Improved performance:• ≈ 40% increase in torque density

• ≈ 1 − 3% increase in efficiency

• “No Voltage Combined Windings”• Better performance at extreme

speeds

© University of Wisconsin Board of Regents 7

Combined Windings

50 kW, 30 kRPM Compressor Optimization

[1] J Chen, J Zhu, E. Severson, “Review of Bearingless Motor Technology for Significant Power Applications,” IEEE Trans on Ind. App., 2020[2] E Severson, et al, “Design of dual purpose no voltage combined windings for bearingless motors,” IEEE Trans. on Ind. App., 2017.

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Enable a Shift in Power-Speed Capability

© University of Wisconsin Board of Regents

[1] D. Gerada et al, “High-speed electrical machines: Technologies, trends, and developments,” IEEE Trans on Ind. Elec., 2013[2] J Chen, J Zhu, E. Severson, “Review of Bearingless Motor Technology for Significant Power Applications,” IEEE Trans on Ind. App., 2020

Highest Speed-Power Bearingless Motors2Highest Speed-Power SPM Motors (with bearings)1

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Turbomachinery Bearingless Motor Concepts

© University of Wisconsin Board of Regents

1) Complete magnetic levitation

2) Hybrid: Conventional bearings + bearingless motor

Bearingless Motor5-DOF Bearingless Motor

2-DOF Bearingless Motor[2]

Conventional

Bearings

Use bearingless motor to improve

rotor dynamics (instead of levitation)

[1] J Chen, J Zhu, E. Severson, “Review of Bearingless Motor Technology for Significant Power Applications,” IEEE Trans on Ind. App., 2020[2] H. Mitterhofer et al, “On the high speed capacity of bearingless drives,” IEEE Trans on Ind. Elec., 2014

• Universities thrive at low TRLs

• Many pathways to funded research:• Industrial sponsored research projects

• Gift funding

• Industry consortia

• Collaboration on federal grants and SBIR/STTR

• IP agreements can be difficult, but the trend is toward more flexible terms

University Research Needed:

• Electric machine design• New topologies and concepts (i.e.,

magnet-free, hybrid)• Design optimization

• Power electronics• Advanced topologies to reduce cost,

increase efficiency• Meet unique needs of new electric

machinery

• Control• Self-sensing• Precise actuation

• Rotor dynamics

© University of Wisconsin Board of Regents 10

Role of Universities

Thank you!

© University of Wisconsin Board of Regents 11Assistant Professor Eric Severson